/*
   MD5()

    Computes the MD5 hash for the given input data

    input :  data as String - (Assumes Unicode code points are encoded as UTF-8. If you 
                               attempt to digest Unicode strings using other encodings 
                               you will get incorrect results!)

             data as array of characters - (Assumes Unicode code points are encoded as UTF-8. If you 
                              attempt to digest Unicode strings using other encodings 
                              you will get incorrect results!)

             data as array of bytes (plain javascript array of integer numbers)

             data as ArrayBuffer (see: https://developer.mozilla.org/en/JavaScript_typed_arrays)
            
             data as Float32Array, Float64Array, Int16Array, Int32Array, Int8Array, Uint16Array, Uint32Array or Uint8Array (see: https://developer.mozilla.org/en/JavaScript_typed_arrays)
             
             (DataView is not supported yet)

   output: MD5 hash (as Hex Uppercase String)
*/

function MD5(data) {
  // convert number to (unsigned) 32 bit hex, zero filled string
  function to_zerofilled_hex(n) {
    var t1 = (n >>> 0).toString(16)
    return "00000000".substr(0, 8 - t1.length) + t1
  }

  // convert array of chars to array of bytes 
  function chars_to_bytes(ac) {
    var retval = []
    for (var i = 0; i < ac.length; i++) {
      retval = retval.concat(str_to_bytes(ac[i]))
    }
    return retval
  }

  // convert a 64 bit unsigned number to array of bytes. Little endian
  function int64_to_bytes(num) {
    var retval = []
    for (var i = 0; i < 8; i++) {
      retval.push(num & 0xFF)
      num = num >>> 8
    }
    return retval
  }

  //  32 bit left-rotation
  function rol(num, places) {
    return ((num << places) & 0xFFFFFFFF) | (num >>> (32 - places))
  }

  // The 4 MD5 functions
  function fF(b, c, d) {
    return (b & c) | (~b & d)
  }

  function fG(b, c, d) {
    return (d & b) | (~d & c)
  }

  function fH(b, c, d) {
    return b ^ c ^ d
  }

  function fI(b, c, d) {
    return c ^ (b | ~d)
  }

  // pick 4 bytes at specified offset. Little-endian is assumed
  function bytes_to_int32(arr, off) {
    return (arr[off + 3] << 24) | (arr[off + 2] << 16) | (arr[off + 1] << 8) | (arr[off])
  }

  /*
  Conver string to array of bytes in UTF-8 encoding
  See: 
  http://www.dangrossman.info/2007/05/25/handling-utf-8-in-javascript-php-and-non-utf8-databases/
  http://stackoverflow.com/questions/1240408/reading-bytes-from-a-javascript-string
  How about a String.getBytes(<ENCODING>) for Javascript!? Isn't it time to add it?
  */
  function str_to_bytes(str) {
    var retval = []
    for (var i = 0; i < str.length; i++)
      if (str.charCodeAt(i) <= 0x7F) {
        retval.push(str.charCodeAt(i))
      } else {
        var tmp = encodeURIComponent(str.charAt(i)).substr(1).split('%')
        for (var j = 0; j < tmp.length; j++) {
          retval.push(parseInt(tmp[j], 0x10))
        }
      }
    return retval
  }

  // convert the 4 32-bit buffers to a 128 bit hex string. (Little-endian is assumed)
  function int128le_to_hex(a, b, c, d) {
    var ra = ""
    var t = 0
    var ta = 0
    for (var i = 3; i >= 0; i--) {
      ta = arguments[i]
      t = (ta & 0xFF)
      ta = ta >>> 8
      t = t << 8
      t = t | (ta & 0xFF)
      ta = ta >>> 8
      t = t << 8
      t = t | (ta & 0xFF)
      ta = ta >>> 8
      t = t << 8
      t = t | ta
      ra = ra + to_zerofilled_hex(t)
    }
    return ra
  }

  // conversion from typed byte array to plain javascript array 
  function typed_to_plain(tarr) {
    var retval = new Array(tarr.length)
    for (var i = 0; i < tarr.length; i++) {
      retval[i] = tarr[i]
    }
    return retval
  }

  // check input data type and perform conversions if needed
  var databytes = null
    // String
  var type_mismatch = null
  if (typeof data == 'string') {
    // convert string to array bytes
    databytes = str_to_bytes(data)
  } else if (data.constructor == Array) {
    if (data.length === 0) {
      // if it's empty, just assume array of bytes
      databytes = data
    } else if (typeof data[0] == 'string') {
      databytes = chars_to_bytes(data)
    } else if (typeof data[0] == 'number') {
      databytes = data
    } else {
      type_mismatch = typeof data[0]
    }
  } else if (typeof ArrayBuffer != 'undefined') {
    if (data instanceof ArrayBuffer) {
      databytes = typed_to_plain(new Uint8Array(data))
    } else if ((data instanceof Uint8Array) || (data instanceof Int8Array)) {
      databytes = typed_to_plain(data)
    } else if ((data instanceof Uint32Array) || (data instanceof Int32Array) ||
      (data instanceof Uint16Array) || (data instanceof Int16Array) ||
      (data instanceof Float32Array) || (data instanceof Float64Array)
    ) {
      databytes = typed_to_plain(new Uint8Array(data.buffer))
    } else {
      type_mismatch = typeof data
    }
  } else {
    type_mismatch = typeof data
  }

  if (type_mismatch) {
    alert('MD5 type mismatch, cannot process ' + type_mismatch)
  }

  function _add(n1, n2) {
    return 0x0FFFFFFFF & (n1 + n2)
  }

  return do_digest()

  function do_digest() {
    // function update partial state for each run
    function updateRun(nf, sin32, dw32, b32) {
      var temp = d
      d = c
      c = b
        //b = b + rol(a + (nf + (sin32 + dw32)), b32)
      b = _add(b,
        rol(
          _add(a,
            _add(nf, _add(sin32, dw32))
          ), b32
        )
      )
      a = temp
    }

    // save original length
    var org_len = databytes.length

    // first append the "1" + 7x "0"
    databytes.push(0x80)

    // determine required amount of padding
    var tail = databytes.length % 64
      // no room for msg length?
    if (tail > 56) {
      // pad to next 512 bit block
      for (var i = 0; i < (64 - tail); i++) {
        databytes.push(0x0)
      }
      tail = databytes.length % 64
    }
    for (i = 0; i < (56 - tail); i++) {
      databytes.push(0x0)
    }
    // message length in bits mod 512 should now be 448
    // append 64 bit, little-endian original msg length (in *bits*!)
    databytes = databytes.concat(int64_to_bytes(org_len * 8))

    // initialize 4x32 bit state
    var h0 = 0x67452301
    var h1 = 0xEFCDAB89
    var h2 = 0x98BADCFE
    var h3 = 0x10325476

    // temp buffers
    var a = 0,
      b = 0,
      c = 0,
      d = 0

    // Digest message
    for (i = 0; i < databytes.length / 64; i++) {
      // initialize run
      a = h0
      b = h1
      c = h2
      d = h3

      var ptr = i * 64

      // do 64 runs
      updateRun(fF(b, c, d), 0xd76aa478, bytes_to_int32(databytes, ptr), 7)
      updateRun(fF(b, c, d), 0xe8c7b756, bytes_to_int32(databytes, ptr + 4), 12)
      updateRun(fF(b, c, d), 0x242070db, bytes_to_int32(databytes, ptr + 8), 17)
      updateRun(fF(b, c, d), 0xc1bdceee, bytes_to_int32(databytes, ptr + 12), 22)
      updateRun(fF(b, c, d), 0xf57c0faf, bytes_to_int32(databytes, ptr + 16), 7)
      updateRun(fF(b, c, d), 0x4787c62a, bytes_to_int32(databytes, ptr + 20), 12)
      updateRun(fF(b, c, d), 0xa8304613, bytes_to_int32(databytes, ptr + 24), 17)
      updateRun(fF(b, c, d), 0xfd469501, bytes_to_int32(databytes, ptr + 28), 22)
      updateRun(fF(b, c, d), 0x698098d8, bytes_to_int32(databytes, ptr + 32), 7)
      updateRun(fF(b, c, d), 0x8b44f7af, bytes_to_int32(databytes, ptr + 36), 12)
      updateRun(fF(b, c, d), 0xffff5bb1, bytes_to_int32(databytes, ptr + 40), 17)
      updateRun(fF(b, c, d), 0x895cd7be, bytes_to_int32(databytes, ptr + 44), 22)
      updateRun(fF(b, c, d), 0x6b901122, bytes_to_int32(databytes, ptr + 48), 7)
      updateRun(fF(b, c, d), 0xfd987193, bytes_to_int32(databytes, ptr + 52), 12)
      updateRun(fF(b, c, d), 0xa679438e, bytes_to_int32(databytes, ptr + 56), 17)
      updateRun(fF(b, c, d), 0x49b40821, bytes_to_int32(databytes, ptr + 60), 22)
      updateRun(fG(b, c, d), 0xf61e2562, bytes_to_int32(databytes, ptr + 4), 5)
      updateRun(fG(b, c, d), 0xc040b340, bytes_to_int32(databytes, ptr + 24), 9)
      updateRun(fG(b, c, d), 0x265e5a51, bytes_to_int32(databytes, ptr + 44), 14)
      updateRun(fG(b, c, d), 0xe9b6c7aa, bytes_to_int32(databytes, ptr), 20)
      updateRun(fG(b, c, d), 0xd62f105d, bytes_to_int32(databytes, ptr + 20), 5)
      updateRun(fG(b, c, d), 0x2441453, bytes_to_int32(databytes, ptr + 40), 9)
      updateRun(fG(b, c, d), 0xd8a1e681, bytes_to_int32(databytes, ptr + 60), 14)
      updateRun(fG(b, c, d), 0xe7d3fbc8, bytes_to_int32(databytes, ptr + 16), 20)
      updateRun(fG(b, c, d), 0x21e1cde6, bytes_to_int32(databytes, ptr + 36), 5)
      updateRun(fG(b, c, d), 0xc33707d6, bytes_to_int32(databytes, ptr + 56), 9)
      updateRun(fG(b, c, d), 0xf4d50d87, bytes_to_int32(databytes, ptr + 12), 14)
      updateRun(fG(b, c, d), 0x455a14ed, bytes_to_int32(databytes, ptr + 32), 20)
      updateRun(fG(b, c, d), 0xa9e3e905, bytes_to_int32(databytes, ptr + 52), 5)
      updateRun(fG(b, c, d), 0xfcefa3f8, bytes_to_int32(databytes, ptr + 8), 9)
      updateRun(fG(b, c, d), 0x676f02d9, bytes_to_int32(databytes, ptr + 28), 14)
      updateRun(fG(b, c, d), 0x8d2a4c8a, bytes_to_int32(databytes, ptr + 48), 20)
      updateRun(fH(b, c, d), 0xfffa3942, bytes_to_int32(databytes, ptr + 20), 4)
      updateRun(fH(b, c, d), 0x8771f681, bytes_to_int32(databytes, ptr + 32), 11)
      updateRun(fH(b, c, d), 0x6d9d6122, bytes_to_int32(databytes, ptr + 44), 16)
      updateRun(fH(b, c, d), 0xfde5380c, bytes_to_int32(databytes, ptr + 56), 23)
      updateRun(fH(b, c, d), 0xa4beea44, bytes_to_int32(databytes, ptr + 4), 4)
      updateRun(fH(b, c, d), 0x4bdecfa9, bytes_to_int32(databytes, ptr + 16), 11)
      updateRun(fH(b, c, d), 0xf6bb4b60, bytes_to_int32(databytes, ptr + 28), 16)
      updateRun(fH(b, c, d), 0xbebfbc70, bytes_to_int32(databytes, ptr + 40), 23)
      updateRun(fH(b, c, d), 0x289b7ec6, bytes_to_int32(databytes, ptr + 52), 4)
      updateRun(fH(b, c, d), 0xeaa127fa, bytes_to_int32(databytes, ptr), 11)
      updateRun(fH(b, c, d), 0xd4ef3085, bytes_to_int32(databytes, ptr + 12), 16)
      updateRun(fH(b, c, d), 0x4881d05, bytes_to_int32(databytes, ptr + 24), 23)
      updateRun(fH(b, c, d), 0xd9d4d039, bytes_to_int32(databytes, ptr + 36), 4)
      updateRun(fH(b, c, d), 0xe6db99e5, bytes_to_int32(databytes, ptr + 48), 11)
      updateRun(fH(b, c, d), 0x1fa27cf8, bytes_to_int32(databytes, ptr + 60), 16)
      updateRun(fH(b, c, d), 0xc4ac5665, bytes_to_int32(databytes, ptr + 8), 23)
      updateRun(fI(b, c, d), 0xf4292244, bytes_to_int32(databytes, ptr), 6)
      updateRun(fI(b, c, d), 0x432aff97, bytes_to_int32(databytes, ptr + 28), 10)
      updateRun(fI(b, c, d), 0xab9423a7, bytes_to_int32(databytes, ptr + 56), 15)
      updateRun(fI(b, c, d), 0xfc93a039, bytes_to_int32(databytes, ptr + 20), 21)
      updateRun(fI(b, c, d), 0x655b59c3, bytes_to_int32(databytes, ptr + 48), 6)
      updateRun(fI(b, c, d), 0x8f0ccc92, bytes_to_int32(databytes, ptr + 12), 10)
      updateRun(fI(b, c, d), 0xffeff47d, bytes_to_int32(databytes, ptr + 40), 15)
      updateRun(fI(b, c, d), 0x85845dd1, bytes_to_int32(databytes, ptr + 4), 21)
      updateRun(fI(b, c, d), 0x6fa87e4f, bytes_to_int32(databytes, ptr + 32), 6)
      updateRun(fI(b, c, d), 0xfe2ce6e0, bytes_to_int32(databytes, ptr + 60), 10)
      updateRun(fI(b, c, d), 0xa3014314, bytes_to_int32(databytes, ptr + 24), 15)
      updateRun(fI(b, c, d), 0x4e0811a1, bytes_to_int32(databytes, ptr + 52), 21)
      updateRun(fI(b, c, d), 0xf7537e82, bytes_to_int32(databytes, ptr + 16), 6)
      updateRun(fI(b, c, d), 0xbd3af235, bytes_to_int32(databytes, ptr + 44), 10)
      updateRun(fI(b, c, d), 0x2ad7d2bb, bytes_to_int32(databytes, ptr + 8), 15)
      updateRun(fI(b, c, d), 0xeb86d391, bytes_to_int32(databytes, ptr + 36), 21)

      // update buffers
      h0 = _add(h0, a)
      h1 = _add(h1, b)
      h2 = _add(h2, c)
      h3 = _add(h3, d)
    }
    // Done! Convert buffers to 128 bit (LE)
    return int128le_to_hex(h3, h2, h1, h0).toUpperCase()
  }
}
exports.MD5 = MD5;